It has become well established that there are major public health benefits from early detection and treatment of disease of internal organs (such as the colon, esophagus, stomach, urethra, bladder, ureter, kidney, lungs, bronchi, uterus, and other organ systems) and of various body passageways (such as the alimentary and excretory canals and airways). Early detection of such diseases can be accomplished by periodic medical examinations aided by modern medical procedures and devices such as an endoscope. A conventional imaging endoscope generally comprises a flexible tube with a fiber optic light guide that directs illuminating light from an external light source to the distal tip where it illuminates the region inside the body of the patient to be examined. Frequently, additional optical components are incorporated to adjust the spread of the light exiting the fiber or fiber bundle and the distal tip. An objective lens and fiber optic imaging light guide communicating with a camera at the proximal end of the endoscope, or an imaging camera chip at the distal tip, produce an image that is displayed to the operator. In addition, most endoscopes include one or more working channels through which medical devices such as biopsy forceps, snares, fulguration probes, and other tools may be passed.
Some endoscopes and electrophysiology catheters can steer or deflect the distal tip of the endoscope to follow the pathway of the anatomy under examination such as the colon, bladder, kidney, and heart. Deflection or articulation is often a desirable characteristic in these types of medical devices to minimize friction force and trauma to the surrounding tissue, and to survey targeted examination sites. Navigation of the endoscope through various areas within a patient improves the success of the examination and minimizes pain, side effects, risk, or sedation to the patient.
In order to achieve active deflection at the distal flexible portion of the device, most endoscopes use a force created on one end of the device, usually at a handle. The three is then transmitted to the articulation section by control cables or pull-wires. The pull-wires are carried within the endoscope shaft connecting the distal end to a set of controls in the handle. By manipulating the controls, the operator is able to steer the distal portion of the endoscope during insertion and direct it to a region of interest within the body of the patient.
The mechanism of deflection varies amongst steerable endoscopes and catheters. Some articulating sections are made of elastic elements, such as for example, Pebax®. When the force is applied through the pull-wires, one side of the element can deform (i.e., compress or stretch) resulting in bending. The consistency of bending plane of these devices would depend on such factors as, for example, material homogeneity, or the manufacturing process, for example molding or extrusion. Therefore, the bending consistency with such devices typically is far less than ideal. Also, these devices generally are not designed to transmit a torque from one end to the other. They tend to twist when torqued.
Other articulating designs consist of many separate elements, links, each of which has a pivoting point. Under the applied force, each link would turn around a pivoting point relative to each other. Such devices keep the bending plane much more consistently.
There are many design and performance challenges inherent in these known devices. Some of these challenges include achieving planar deflection at the tip as well as preventing the shaft from buckling or forming a series of “S” shapes from the tension of pull-wire mechanisms. Other challenges include being able to keep an individual bend in one plane, achieving the appropriate amount of angular deflection, and achieving multiple directions of deflection.
Typically, flexible endoscopes are very expensive medical devices. Because of the expense, these endoscopes are built to withstand multiple uses upon many patients and repeated disinfections. Conventional endoscopes are generally built of strong composite material structures such as metals and plastics that do not degrade under repeated cleaning and high temperatures. These material structures decrease the flexibility of the endoscope and can compromise patient comfort. Furthermore, conventional endoscopes are typically complex and fragile instruments that frequently need expensive repair as a result of damage during use or during a disinfection procedure.